Removable core differential mechanism

ABSTRACT

A differential mechanism for a lock cylinder that retains a core within the cylinder and is selectively operable for the removal of the core from the lock cylinder. Two or more retaining links hold the core within the lock body by their engagement with an annular groove in the body. During normal lock operation, one of the retaining links is cammed out of engagement with the annular groove at a core removal rotational index position while the other link(s) remain engaged in the groove. Removal of the core is accomplished by the provision of a central pivot for a link retractor thereby causing all of the remaining links to be retracted out of engagement with the body groove when any one of such links is cammed out of the body groove at a core removal index position. A key for normal operation of the lock cylinder and an axle selectively attachable thereto is provided as a combined means to rotate the core within the lock body, actuate the differential mechanism to a core releasing condition and withdraw the core from the lock cylinder body.

United States Patent [1 1 Roberts [4 1 Sept. 16, 1975 REMOVABLE CORE DIFFERENTIAL MECHANISM [75] Inventor: Marvin E. Roberts, Reno, Nev.

[73] Assignee: Locking Systems, Inc., Reno, Nev.

[22] Filed: Apr. 5, 1974 21 Appl. No.: 458,412

[52] US. Cl. 70/368; 70/369; 70/395 [51] Int. Cl. EQSB 9/04 [58] Field of Search 70/367, 368,v 369, 371, 70/395, 397

[56] References Cited UNITED STATES PATENTS 3,434,316 3/l969 Neary 70 371 Primary Examiner-Robert L. Wolfe [57] ABSTRACT A differential mechanism for a lock cylinder that retains a core within the cylinder and is selectively operable for the removal of the core from the lock cylinder. Two or more retaining links hold the core within the lock body by their engagement with an annular groove in the body. During normal lock operation, one of the retaining links is cammed out of engagement with the annular groove at a core removal rotational index position while the other link(s) remain engaged in the groove. Removal of the core is accomplished by the provision of a central pivot for a link retractor thereby causing all of the remaining links to be retracted out of engagement with the body groove when any one of such links is cammed out of the body groove at a core removal index position. A key for normal operation of the lock cylinder and an axle selectively attachable thereto is provided as a combined means to rotate the core within the lock body, actuate the differential mechanism to a. core releasing condition and withdraw the core from the lock cylinder body.

10 Claims, 7 Drawing Figures REMOVABLE CORE DIFFERENTIAL MECHANISM BACKGROUND OF THE INVENTION wherein the lock core can be removed from the lock A cylinder without access to the 'rear thereof and without disassembly of any of the boltwork or other hardware associated with the lock cylinder.

One method commonly in use is to provide a set of special core-removal combinations within groups of locks and a special control key to operate these special combinations thus permitting the removal and interchangeability of the cores within each group. This system requires a complex structure. Compromise of a control key permits access through all of the locks in its group.

Another method of achieving removable core capability in lock cylinders incorporates holding detents within the core or cylinder body with access holes in the face of the lock for the insertion of special tools, wires, etc., to move the detent out of holding engagement. This method does not require the use of special control keys but the obvious access holes invite insertion of extrinsic objects that often block the proper removal tools from disengaging the detent. The very presence of such holes motivates the curious to explore their purpose which often results in successful core removal and at times interchanging of cores between locks within a system such as by students in dormitories or locker rooms.

For these and other reasons, it is evident that a need exists for an improved removable core mechanism to which the invention addresses itself.

SUMMARY OF THE INVENTION In general there is provided herein a differential mechanism for incorporation within a lock cylinder to retain the core within the cylinder and to selectively permit the removal of the core from the cylinder body through the front opening thereof. The mechanism also permits the installation of the core into the cylinder body with only the parts being assembled required to accomplish the operation.

The differential mechanism consists of two or more links extendible chordally from a lock core into a retaining groove or surface of the lock cylinder body and retractable against Spring bias to a position flush with the cylindrical outer surface of the core. The links are intermeshed with a common link retractor which is aligned to receive an axle or other reaction means when the core is locked from relative rotation with the lock body.

At least one cam surface is provided in the cylinder body and in normal lock operation each link upon contacting said surface is cammed out of engagement with the body which causes the link retractor to rotate out of a center position thereby permitting the other links to remain engaged with the body. When an axle or other reaction means is provided and the core is rotated within the body, the link retractor is caused to be rotated about a fixed center by'action of any cammed link thereby causing the other links to be retracted out of engagement with the body which releases the core for removal from the lock cylinder body.

With the core removed from the lock cylinder body the links can all be depressed against their spring bias by finger pressure until they are flush with the cylindrical outer surface of the core. The core can then be inserted into the cylinder body and pushed back until the links are aligned with the body groove or retaining surface at which time the links will spring chordally outwardly into engagement with the body groove or retaining surface thereby retaining the core within the cylinder body during normal lock operation.

A key and selectively attachable axle or other reaction means is further provided in the invention which axle when attached to the key and used cooperatively therewith in the operation of the lock cylinder when core removal is desired. When the axle is detached from the keythe key alone is used in the normal operation of the lock cylinder.

OBJECTS OF THE INVENTION It is the general object of the invention to provide an improved removable core mechanism for incorporation in a lock cylinder and more particularly to provide an improved removable core mechanism which permits removal of the core from the front of the lock cylinder without access to any of the lock cylinders associated boltwork or related hardware.

A further object of the invention is to provide an improved removable core mechanism for use in cooperation with a normal operating key that is coded to the individual code of its associated lock cylinder without resort to a control key which is normally coded for use in a plurality of locks.

A further object of the invention is to provide an improved removable core mechanism that retains the core in the lock cylinder at all rotational positions of the core when the lock is operated in the normal manner.

A further object of the invention is to provide an improved removable core mechanism wherein the releasing mechanism is selectively rendered operable prior to the operation of the core for its removal from the lock cylinder.

A further object of the invention is to provide an improved removable core mechanism which permits installation of the core into the lock cylinder without resort to a key, wire, tool or any special device other than the parts being assembled.

A further object of the invention is to provide an improved removable core mechanism which is differential in operation, serving to retain the core in the lock cylinder in normal operation of the lock, and, when selectively operated with the interposition of an axle or other reaction means, serving to release the core for removal from the lock cylinder.

A further object of the invention is to provide an improved key with a selectively attachable axle or other reaction means for the releasing operation of a differential mechanism in a removable core of a lock cylinder.

A further object of the invention is to provide an improved removable core mechanism within a lock cylinder that may be readily installed in existing locksets and other lock operated devices.

A further object of the invention is to provide an improved removable core mechanism that is adaptable for incorporation into lock cylinders with different types of tumbler mechanisms such as those associated with wafer tumblers, lever tumblers, axial and certain radial pin tumblers, rotary disc tumblers and others whose locking means are substantially contained within the core thereof. An example of a rotary disc tumbler lock wherein the improved removable core mechanism is adaptable thereto is contained in US. Pat. No. 3,789,638, Roberts, Cohn and Ward, Rotary Disc Tumbler Lock Construction, dated Feb. 5, 1974.

A further object of the invention is to provide an improved removable core mechanism for a lock cylinder that is simple and economical to manufacture.

The foregoing and other objects of the invention will become more readily evident from the following detailed description of a preferred embodiment when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section on a vertical, axial plane through a lock cylinder adapted with a removable core differential mechanism.

FIG. 2 is a side view of a key with an axle attached to the lead end thereof and with a portion of the key bow broken away to reduce the size of the figure. FIG. 3 is a side view of the lead end portion of the key in FIG. 2 showing the axle detached therefrom, portions of the key being broken away to reduce the size of the figure.

FIG. 4 is a cross sectional view taken along lines 4, 4 of FIG. 1 showing the differential mechanism with the core in a normally locked position.

FIG. 5 is a cross sectional view taken along lines 5, 5 of FIG. 1 showing the diflerential mechanism with the core rotated to a removal position and with a portion of the mechanism engaged to prevent removal of the core.

FIG. 6 is a cross sectional view taken along lines 6, 6 of FIG. 1 showing the differential mechanism with the core rotated to a removal position and the mechanism disengaged to permit removal of the core.

FIG. 7 is a front view taken along lines 7, 7 of FIG. 1 showing the key receiving opening and the axle receiving hole at the rear of the tumbler assembly within the core.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a lock cylinder 10 of the type, for example, used in key-in-knob locksets, containing a body 16 with a generally cylindrical opening 30 therethrough, a body groove 19 extending radially outward of opening 30, a body annular groove or retaining portion 26; a core housing 17 with a front flange 25 that is substantially in confronting relationship with the front of body 16 with the core 17 assembled for normal operation, an assembly within core 17 consisting of: a plurality of tumblers 21; a sidebar 18 contained on all sides by a slot in core 17 and, when cylinder 10 is in a locked condition, extending radially into body groove 19 thereby preventing relative rotation of core 17 within body 16; a centering spring 22 that serves to drive the tumblers 21 to scrambled positions when the tumblers 21 are free from key contact; a differential mechanism consisting of a differential carrier 31, a link retractor 32, links 34 extendable through slots 47 in core 17 as best shown in FIG. 4, link ends 35 serving to retain core 17 and its associated assembly within body 16 when ends 35 are engaged with annular groove 26, and differential retainer 33 serving to restrict longitudinal axial movement of the differential mechanism within core 17; a driving bar 23 which is held in rotational alignment with core 17 as, for example, by a tab similar to tab 45 of carrier 31 that is interposed in tab slot 46 of core 17 as best shown in FIG. 4; and retaining ring 24 serving to retain the assembly within core 17.

The differential carrier 31, retractor 32 and retainer 33 each have a hole 37, 38, and 39 respectively at their central axial positions, holes 37 and 39 providing centrally located bearings for axle l3 and hole 38 providing a central opening for axle 13 about which retractor 32 rotates when the differential mechanism is operated to release core 17 from body 16.

Now referring to' FIG. 2, axle 13 is attached to the lead end of key 11 and remains in this condition when the lock is operated to activate the differential mechanism for release of core 17 from body 16 and removal therefrom. Key bits 12 are cut to the corresponding code of an associated lock cylinder or cylinders.

Axle 13 is detachable from key 11 as, for example, by the disengagement of threaded portion 14 of axle 13 from tapped portion 15 of key 11 as shown in FIG. 3 and axle 13 as detached from key 11 is not used in the normal operation of lock cylinder 10 wherein core 17 is retained within body 16.

Now referring to FIG. 4, carrier 31 is held in rotational alignment with core 17 by tabs 45 which are interposed in tab slots 46 of core 17. A camming portion 27, located in body annular groove 26, has an inward surface 28 that is common with the internal surface of opening 30 and the camming portion 27 is at an angular distance 29 from any link end 35 when core 17 is locked from relative rotation with body 16. In the condition as shown in FIG. 4 wherein core 17 is rotationally locked with body 16, differential links 34 extend chordally outward of core 17 as biased by springs 36 with link ends 35 engaged with groove 26, link retractor 32 is centrally located within carrier 31 by the reaction of teeth 42 with tooth openings 44 and holes 37, 38, and 39 are in axial alignment thus providing a clear opening for the insertion of axle 13 thereinto.

Now referring to FIG. 5, when a correspondingly coded key 11 with axle l3 detached therefrom is used to operate lock cylinder 10, core 17 is rotated in body 16 and rotationally carries with it differential carrier 31, links 34, springs 36 and retractor 32. When one of the link ends 35 contacts cam portion 27 its associated link 34 is cammed chordally inwardly against the bias of its associated spring 36 until that end 35 is disengaged from groove 26 by cam surface 28 while the other link 34 remains chordally extended outwardly by the bias of its associated spring 36 with its associated end 35 engaged into groove 26 and retractor 32 is rotated out of an axially central position by the reaction of teeth 42 in tooth openings 44 of links 34.

Any link end 35 is cammed chordally inwardly as it comes into contact with a cam portion 27 during the clockwise or counterclockwise rotation of core 17 and, when the rotation of core 17 carries each link end 35 out of contact with a cam portion 27, that end 35 returns into engagement with groove 26 by the bias of its associated spring 36 urging its associated link 34 chordally outwardly.

During the lock operation as described in the two paragraphs immediately above, the differential mechanism retains core 17 withinbody 16 by the engagement holes 37, 38, and 39 of differential carrier 31, retractor 32 and retainer 33 respectively, axle 13 serving as a central pivot for retractor 32 with axle 13 supported by holes 37 and 39 in addition to such support key 1 1 may impart thereto. As core 17 is rotated in body 16, core 17 rotationally carries with it differential carrier 31, links 34, springs 36 and retractor 32. When one of the link ends 35 comes into contact with a cam portion 27 its associated link 34 is cammed chordally inwardly against the bias of its associated spring 36 until that end 35 is disengaged from groove 26 by cam surface 28. Retractor 32 is rotated about axle 13 by the displacement of tooth 42 as carried by tooth opening 44 of cammed link 34. The opposite tooth 42 of retractor 32 causes the other link 34 to retract chordally inwardly by reaction with that link s associated tooth opening 44 thereby causing its associated link end 35 to disengage from groove 26 which releases core 17 and its associated assembly for withdrawal from body 16.

A plurality of cam portions 27 may be included in a given lock cylinder thereby providing more than one removal rotational positions of core 17 with the multiple cam portions 27 located at angular distances within groove 26 to prevent simultaneous contact at any rotational position of core 17 of link ends 35 with the multiple cam positions 27 so provided.

When core 17 and its associated assembly is exterior of body 16, link ends 35 extend beyond the outer cylindrical surface of core 17 by reason of the bias of their springs 36 and are depressible until they are flush with core 17. Core 17 can then be axially inserted into body 16 and pushed back until link ends 35 are substantially in the same plane as groove 26 where they will extend chordally outwardly into engagement with groove 26 being urged by the bias of springs 36.

It is understood, obviously, that the particular application for use of this removable core differential mechanism is not believed part of the invention nor should it be considered limiting thereto since it is readily evident that the invention can be used in a wide range of applications.

From the foregoing, it will be readily apparent that there has been provided an improved removable core retention and release mechanism for incorporation in lock cylinders. This mechanism is operable differentially, in one condition serving to retain the lock core at all rotational positions thereof within the lock cylinder and in another condition, wherein a centrally located axial pivot is provided, serving to release the lock core at one or more rotational positions thereof for removal from the lock cylinder.

I claim:

I. A removable core differential mechanism for a lock cylinder, said cylinder having a body with a generally cylindrical opening therein, a retaining surface extending radially outwardly of said body opening, one or more cam surfaces extending radially inwardly of said retaining surface to a level substantially flush with said body opening, a core with a flange on one end thereof, said core being insertable into said body opening until said flange is in substantial confronting relationship with the face of saidbody opening, said core containing an assembly including one or more tumbler elements, means serving to releasably lock said core in relative rotation to said body, means serving to translate rotation of said core to associated latching means, a differential mechanism serving to retain said core within said body and to selectively r'elease saidcore for removal from said body, closing means serving to retain said assembly substantially within said core, said differential mechanism consisting of a -carrier or housing rotationally fixed in relation tosaid core, a plurality of links movable chordally to said carrier, portions of said links extendible outwardly of the ;-wall of said core through slots therein, said links being yieldingly urged in an outward direction, said slots in cooperation .with said carrier maintaining said-links invrelative rotational and axial alignment with said core, said extendible portions of said links engaging said retaining surface of said body serving to retain said core within said body, a link retracting means engaging each of said links and selectively operable, by the provision of a centrally located reaction means, to retract the remaining of said links from engagement with said retaining surface when any one of said links is urged out of engagement with said retaining surface by one of said cam surfaces.

2. A mechanism according to claim 1, including a key adapted to operate said core in said body for relative rotation therebetween, said key being further adapted to releasibly retain said reaction means for selective attachment thereto.

3. A mechanism according to claim 1, including a key adapted to operate said core for relative rotation with said body, said key being adapted to selectively impose said reaction means into cooperative engagement with said reaction means.

4. A mechanism according to claim 1, wherein, when said removable core is exterior of said body, said links, being yieldingly urged outwardly of said core, are depressible inwardly against their yielding bias out of positions restricting insertion of said core into said body.

5. A removable core differential mechanism in a lock cylinder, said cylinder including a cylinder body having an opening adapted to receive a removable core therein, said core containing a releasable locking means selectively operable by a key or other means to release said locking means for rotation of said core relative to said body, a plurality of engaging means independent of said locking means, said engaging means releasibly retaining said core Within said body, camming means serving to cam said engaging means one at a time out of engagement with said body at one or more rotational positions of said core relative to said body, retracting means cooperating with each of said engaging means, said retracting means adapted to cooperate with a reaction means to retract the remaining of said engaging means out of engagement with said body when any one of said engaging means is urged out of engagement with said body by said camming means, said reaction means adapted to be selectively interposed into cooperation with said retracting means.

6. A mechanism according to claim 4 wherein said key is adapted to selectively cooperate with said reaction means in the interposition of said reaction means into cooperative engagement with said retracting means.

7. A mechanism according to claim 4 wherein the interposition of said reaction means into cooperative engagement with said retracting means precedes rotation of said core to a rotary release position within said body for the removal of said core therefrom.

8. A mechanism according to claim 4, wherein, when said removable core is exterior of said body, said engaging means, being yieldingly urged outwardly of said core, are depressible inwardly against their yielding bias out of positions restricting insertion of said core into said body.

9. A removable core differential mechanism in a lock cylinder, said cylinder including a cylinder body having an opening adapted to receive a removable core therein, said core containing a releasable locking means selectively operable by a key or other means to release said locking means for rotation of said core relative to said body, a plurality of engaging means independent of said locking means, said engaging means releasably retaining said core within said body, camming means serving to cam said engaging means one at a time out of engagement with said body at one or more rotational positions of said core relative to said body, retracting means cooperating with each of said engaging means, said retracting means adapted to cooperate with a reaction means to retract the remaining of said engaging means out of engagement with said body when any one of said engaging means is urged out of engagement with said body by said camming means, said camming means adapted to be selectively interposed into cooperation with said engaging means.

10. A mechanism according to claim 9, wherein, when said removable core is exterior of said body, said engaging means, being yieldingly urged outwardly of said core, are depressible inwardly against their yielding bias out of positions restricting insertion of said core into said body.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,905 ,213

Date September 16, 1975 Inventor) Marvin E. Roberts It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, claim 6, line 1, claim 7, line 1, and column 7,

claim 8, line 1, "claim 4", each occurrence, should read claim 5 Signed and Scaled thisb thirtieth Day of March 1976 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner uj'PatenIs and Trademarks 

1. A removable core differential mechanism for a lock cylinder, said cylinder having a body with a generally cylindrical opening therein, a retaining surface extending radially outwardly of said body opening, one or more cam surfaces extending radially inwardly of said retaining surface to a level substantially flush with said body opening, a core with a flange on one end thereof, said core being insertable into said body opening until said flange is in substantial confronting relationship with the face of said body opening, said core containing an assembly including one or more tumbler elements, means serving to releasably lock said core in relative rotation to said body, means serving to translate rotation of said core to associated latching means, a differential mechanism serving to retain said core within said body and to selectively release said core for removal from said body, closing means serving to retain said assembly substantially within said core, said differential mechanism consisting of a carrier or housing rotationally fixed in relation to said core, a plurality of links movable chordally to said carrier, portions of said links extendible outwardly of the wall of said core through slots therein, said links being yieldingly urged in an outward direction, said slots in cooperation with said carrier maintaining said links in relative rotational and axial alignment with said core, said extendible portions of said links engaging said retaining surface of said body serving to retain said core within said body, a link retracting means engaging each of said links and selectively operable, by the provision of a centrally located reaction means, to retract the remaining of said links from engagement with said retaining surface when any one of said links is urged out of engagement with said retaining surface by one of said cam surfaces.
 2. A mechanism according to claim 1, including a key adapted to operate said core in said body for relative rotation therebetween, said key being further adapted to releasibly retain said reaction means for selective attachment thereto.
 3. A mechanism according to claim 1, including a key adapted to operate said core for relative rotation with said body, said key being adapted to selectively impose said reaction means into cooperative engagement with said reaction means.
 4. A mechanism according to claim 1, wherein, when said removable core is exterior of said body, said links, being yieldingly urged outwardly of saId core, are depressible inwardly against their yielding bias out of positions restricting insertion of said core into said body.
 5. A removable core differential mechanism in a lock cylinder, said cylinder including a cylinder body having an opening adapted to receive a removable core therein, said core containing a releasable locking means selectively operable by a key or other means to release said locking means for rotation of said core relative to said body, a plurality of engaging means independent of said locking means, said engaging means releasibly retaining said core within said body, camming means serving to cam said engaging means one at a time out of engagement with said body at one or more rotational positions of said core relative to said body, retracting means cooperating with each of said engaging means, said retracting means adapted to cooperate with a reaction means to retract the remaining of said engaging means out of engagement with said body when any one of said engaging means is urged out of engagement with said body by said camming means, said reaction means adapted to be selectively interposed into cooperation with said retracting means.
 6. A mechanism according to claim 4 wherein said key is adapted to selectively cooperate with said reaction means in the interposition of said reaction means into cooperative engagement with said retracting means.
 7. A mechanism according to claim 4 wherein the interposition of said reaction means into cooperative engagement with said retracting means precedes rotation of said core to a rotary release position within said body for the removal of said core therefrom.
 8. A mechanism according to claim 4, wherein, when said removable core is exterior of said body, said engaging means, being yieldingly urged outwardly of said core, are depressible inwardly against their yielding bias out of positions restricting insertion of said core into said body.
 9. A removable core differential mechanism in a lock cylinder, said cylinder including a cylinder body having an opening adapted to receive a removable core therein, said core containing a releasable locking means selectively operable by a key or other means to release said locking means for rotation of said core relative to said body, a plurality of engaging means independent of said locking means, said engaging means releasably retaining said core within said body, camming means serving to cam said engaging means one at a time out of engagement with said body at one or more rotational positions of said core relative to said body, retracting means cooperating with each of said engaging means, said retracting means adapted to cooperate with a reaction means to retract the remaining of said engaging means out of engagement with said body when any one of said engaging means is urged out of engagement with said body by said camming means, said camming means adapted to be selectively interposed into cooperation with said engaging means.
 10. A mechanism according to claim 9, wherein, when said removable core is exterior of said body, said engaging means, being yieldingly urged outwardly of said core, are depressible inwardly against their yielding bias out of positions restricting insertion of said core into said body. 